Transcription factors are central for establishing the cell type-specific gene expression patterns that characterize each of the hundreds of different cell types in developing and adult mammals. Transcription factors are often regulated by signaling pathways, which affect the activity of these factors and ensure appropriate transcriptional responses to developmental and environmental cues. Our preliminary studies indicate that a transcription factor central to embryonic stem cell self-renewal, SOX2, is modified by addition of an O-linked N-acetylglucosamine sugar to serine residue 248 and threonine residue 213. This modification is mediated by the enzyme OGT, which is a central player in the nutrient sensing pathway that detects levels of glucose and other nutrients. We propose to investigate the role of this post-translational modification of SOX2 in self-renewal, to better understand how metabolic pathways impact gene expression in pluripotent cells.